Most of the City is provided with municipal sanitary sewer services. The City's original sanitary sewer system was constructed during the early 1960's. Through public and private development, this system has been expanded to a point where most of the City is provided municipal sanitary sewer services.

Sanitary sewage generated in the City is treated at the Clean Water Plant, which is operated by the Southern Clinton County Municipal Utilities Authority (SCCMUA). SCCMUA was formed in the mid-1970s by the City of DeWitt and Bath, DeWitt and Watertown Charter Townships to address the need for a regional wastewater treatment plant. SCCMUA is also responsible for contractually operating and maintaining the sanitary sewer systems in these four communities.

Construction of the Clean Water Plan started in September 1978 with the plant going into operation in October 1980. The Clean Water Plant cost approximately $11,000,000 to construct and is capable of treating up to 5,000,000 gallons of sanitary sewage a day. The City owns approximately twelve percent of the treatment capacity in the Clean Water Plant.

SCCMUA discharges into the Looking Glass River in Clinton County and maintains a current National Pollutant Discharge Eliminating System permit. The operation of SCCMUA is governed by a ten member Board of Commissioners comprised of individuals representing the four constituent municipalities. The City has one representative on this board.

The City's sanitary sewage collection system is comprised of several miles of sanitary sewer lines, force mains and three pumping stations. Residents are billed quarterly for sanitary sewer services based on an adopted residential equivalent unit (reu) schedule. Further information about the City sanitary sewer system, SCCMUA and the Clean Water Plant may be obtained by visiting the SCCMUA web site.